Drying shrinkage cement admixture

Abstract

A cement admixture composition composed of a mixture of alkylene glycol and fume silica to provide a means of inhibiting drying shrinkage and enhancing compressive strength.

What is claimed is: 
     
       1. A cement admixture capable of inhibiting drying shrinkage of a cement composition and enhancing compressive strength of a formation formed from said composition, comprising an aqueous composition containing from 10 to 75 weight percent of a mixture of (A). at least one (i) glycol selected from C 3  -C 12  alkylene glycol or (ii) water-soluble condensed alkylene glycol represented by the formula HO(AO) x  H wherein A is a C 2  -C 4  alkylene or mixtures thereof, O is oxygen and x is a value of from 1 to 20, and mixtures thereof; and   (B). silica fume wherein said components (A) and (B) are in a weight ratio of from 10:1 to 1:10.     
     
     
       2. The admixture of claim 1 wherein said C 3  -C 12  alkylene glycol is represented by the formula HOBOH wherein B is a C 5  -C 8  alkylene group. 
     
     
       3. The admixture of claim 2 wherein said C 3  -C 12  alkylene glycol is represented by the formula ##STR2## wherein each R represents a hydrogen atom or C 1  -C 12  alkyl; each R' represents C 1  -C 2  alkyl; and n represents 1 or 2. 
     
     
       4. The admixture of claim 3 wherein said C 3  -C 12  alkylene glycol is 2-methyl-2,4-pentanediol. 
     
     
       5. The admixture of claim 1 wherein the component (B) is a silica fume by-product of silicon and/or ferrosilicon metal alloy production and the weight ratio of components (A) to (B) is from about 1:1 to 1:5. 
     
     
       6. The admixture of claim 2 wherein the component (B) is a silica fume by-product of silicon and/or ferrosilicon metal alloy production and the weight ratio of component (A) to (B) is from 1:1 to 1:5. 
     
     
       7. The admixture of claim 1 wherein said condensed alkylene glycol is represented by the formula HO(AO) x  H wherein A is a C 2  -C 3  alkylene or mixtures thereof, O is oxygen and x is a value of 1 to 10. 
     
     
       8. The admixture of claim 7 wherein the component (B) is a silica fume by-product of silicon and/or ferrosilicon metal alloy production and the weight ratio of component (A) to (B) is from 1:1 to 1:5. 
     
     
       9. The admixture of claim 1 wherein the aqueous composition further contains a stabilizing amount of an alpha, beta-amino alcohol. 
     
     
       10. A method of inhibiting drying shrinkage of a cement composition while improving compressive strength of an architectural structural formation formed therewith comprising (i) forming a cement composition composed of a hydraulic cement, fine aggregate, coarse aggregate and water with a water to cement weight ratio of from 0.25:1 to 0.7:1;   (ii) adding to said cement composition a cement admixture comprising (A) at least one glycol selected from (i) C 3  -C 12  alkylene glycol or (ii) water-soluble condensed alkylene glycol represented by the formula HO(AO) x  H wherein A is a C 2  -C 4  alkylene or mixtures thereof, O is oxygen and x is a value of from 1 to 20 or mixtures thereof; and   (B) silica fume wherein said components (A) and (B) are in a weight ratio of from 10:1 to 1:10; said cement admixture is added in an amount of from 2 to 25 weight percent based on the weight of the hydraulic cement in said composition.       
     
     
       11. The method of claim 10 wherein said C 3  -C 12  alkylene glycol is represented by the formula HOBOH wherein B is a C 5  -C 8  alkylene group. 
     
     
       12. The method of claim 1 wherein said C 3  -C 12  alkylene glycol is represented by the formula ##STR3## wherein each R represents a hydrogen atom or C 1  -C 2  alkyl; each R' represents C 1  -C 2  alkyl; and n represents 1 or 2. 
     
     
       13. The method of claim 12 wherein said C 3  -C 12  alkylene glycol is 2-methyl-2,4-pentanediol. 
     
     
       14. The method of claim 10 wherein the component (B) is a silica fume by-product of silicon and/or ferrosilicon metal alloy production and the weight ratio of components (A) to (B) is from about 1:1 to 1:5. 
     
     
       15. The method of claim 14 wherein the component (B) is a silica fume by-product of silicon and/or ferrosilicon metal alloy production and the weight of components (A) to (B) is from 1:1 to 1:5. 
     
     
       16. The method of claim 10 wherein said condensed alkylene glycol is represented by the formula HO(AO) x  H wherein A is a C 2  -C 3  alkylene or mixture thereof, O is oxygen and x is a value of 1 to 10. 
     
     
       17. The method of claim 16 wherein the component (B) is a silica fume by-product of silicon and/or ferrosilicon metal alloy production and the weight ratio of component (A) to (B) is from 1:1 to 1:5. 
     
     
       18. The method of claim 10 wherein the admixture further contains a stabilizing amount of an alpha, beta-aminoalcohol.